Synergistic Enhancement Effect of G4 and SN in Gel Polymer Electrolyte Reinforced by PET Nonwoven for Lithium Metal Batteries

Abstract

With the increasing demand for power batteries and energy storage devices, developing solid-state lithium metal batteries (LMBs) with high energy density and outstanding safety is urgent. Gel polymer electrolyte (GPE), a quasi-solid polymer electrolyte (SPE), is a currently promising electrolyte candidate for solid-state LMBs due to its outstanding performance. Herein, a solid-state LMB constructed with a GPE containing tetraethylene glycol dimethyl ether (G4) and succinonitrile (SN) is prepared, whose electrochemical performance is enhanced by synergistic enhancement effect of G4 and SN, and mechanical strength is reinforced by a PET nonwoven supporting layer. G2S2-GPE (a GPE contains the equal weight of G4 and SN) has a high room-temperature ionic conductivity of 0.90 mS cm⁻¹ and Young's modulus of about 200 MPa, as well as enhanced thermal stability (decomposition temperature of 224 °C). Furthermore, the Li||LiFePO₄ full battery can maintain 136.4 mAh g⁻¹ high capacity with a 94.7% capacity retention rate and 99.9% average coulombic efficiency after 800 cycles at 0.5 C. Moreover, high voltage Li||LiNi_0.6Co_0.2Mn_0.2O₂ cell and Li||LiFePO₄ pouch cell employing G2S2-GPE demonstrate satisfactory cycling and safety characteristics, indicating their potential for superior practicability. We believe popularizing this synergistic enhancement strategy in the electrolyte field is beneficial for developing high-performance LMBs.